Access door and frame

ABSTRACT

An access door and frame defining an opening in a ventilating or air conditioning duct including a peripheral frame member incorporating dovetail means to secure easily and rapidly to a metal wall of the duct. The frame includes a peripheral flange of obround configuration which receives and locks the door therein in pressure resisting, air tight junction. The door removably secures to the frame by means of a plurality of readily accessible locks. Both the frame and the door are fabricated to obround configuration to then permit maximum utilization of space with minimum dimensions.

United States Patent [1 1 Kurz [ Nov. 20, 1973 4 22 Filed:

21 Appl. No.: 205,959

[ ACCESS DOOR AND FRAME [75] Inventor: John C. Kurz, Philadelphia, Pa.

[73 Assignee: Advanced Air, Inc., Philadelphia, Pa.

Dec. 8, 1971 [52] US. Cl. 138/92 [51] Int. Cl. F16] 55/10 {58] Field of Search 138/92; 248/27;

49/463, 380; 220/3.8, 85 SP, 55 G, 55 W, 55 N; 52/19, 221, 27, 35; 285/424; 292/DIG.

[56] References Cited UNITED STATES PATENTS 2,936,092 5/1960 Johnson 220/3.8 1,395,807 11/1921 Fomi 220/3.8 2,963,783 12/1960 Field 285/424 708,406 9/1902 Ribison 292/D1G. 20

Primary Examiner-Samuel B. Rothberg Assistant ExaminerSteven M. Pollard Attorney-Karl L. Spivak [57 ABSTRACT An access door and frame defining an opening in a ventilating or air conditioning duct including a peripheral frame member incorporating dovetail means to secure easily and rapidly to a metal wall of the duct. The frame includes a peripheral flange of obround configuration which receives and locks the door therein in pressure resisting, air tight junction. The door removably secures to the frame by means of a plurality of readily accessible locks. Both the frame and the door are fabricated to obround configuration to then permit maximum utilization of space with minimum dimensions.

1 Claim, 4 Drawing Figures ACCESS DOOR AND FRAME BACKGROUND OF THE INVENTION This invention relates generally to the field of building construction, and more particularly, is directed to an access door for providing access to concealed mechanical items within air duct constructions, such as fire dampers.

In the design and construction of buildings, it is the common practice to employ concealed duct systems within the finished walls and ceilings to permit the movement of air to desired locations within the building. Most commonly used air systems employ steel or aluminum ducts of suitable strength and size to accommodate the pressures and volumes of the gases conveyed therein. Such air systems are most usually employed for purposes such as air conditioning, heating, ventilation or certain industrial processes which require the movement of air or other gases.

It is common practice to install fire damper units directly in the duct work at specified, predetermined lo cations to prevent the spread of fire through the duct system. Most municipal building codes and fire insurance standards require fire dampers at each point where the duct pierces a fire division of the building. The usual fire damper units include a frame assembly defining a damper opening and have a blade assembly operable within the frame and including a plurality of blades movable from an open, air passing position wherein the damper opening is substantially unobstructed, to a closed position where the damper opening is closed to prevent the passage of air. In order to retain the blade assembly in the open position, fusible elements of low temperature fuse material have universally been employed for maintaining the blade assembly open under normal thermal conditions within the duct system. When exposed to abnormally high temperatures such as may result from a fire, explosion, or the like, thefusible element melts to release the blade assembly to thereby automatically close the damper opening. As is true with any mechanical device, fire damper fusible links have been known to fail even with out the presence of fire and to thus close the damper opening even when not so desired.

In order to gain entrance to the interior of a duct system to service a fire damper, for example, after a fusible link has failed, it is necessary to employ an access door at each location where a fire damper has been installed. All prior art access doors have tended to be unusually large, and ungainly because of the necessity of having a workman employ both hands in servicing a fire damper unit. All prior art access doors of which I am familiar have been rectangular in configuration and have included lockmeans which were quite difficult to secure and unsecure for access door removal purposes.

Prior art locking devices have usually incorporated wing nuts or nuts and bolts and a workman usually had to employ a screwdriver or other tool to remove the access door from its frame. In the case of a ceiling installation, this meant that a workman frequently had to stand high above floor level to turn the access door securing devices. Because of the ungainly size and weight of the access door, the uncomfortable position of the workman such as when on a ladder and the necessary time required to manually unthread prior art securing devices, the removal of access doors in the past has proved to be quite time consuming and costly, even before undertaking the necessary equipment servicing operations.

SUMMARY OF THE INVENTION The present invention relates to an access door and frame construction suitable for installation in duct work and which are configured to a unique design to permit greatly reduced access door size.

The access door unit of the present invention includes unique locking means for quickly and positively securing an access door to a stationary frame. The locking means are readily openable without the need for any special tools to facilitate removal of the door from its associated frame. The locking means preferable space about the frame to insure undesired partial opening-of the access door after it has been properly seated within the frame and are of the cam operated to assure a leak-free junction capable of withstanding the pressures carried within the duct.

The frame incorporates sound deadening gaskets and securely affixes to the usual duct materials such as aluminum or steel by means of unique integral dove tails which can be rapidly folded to secure the frame in the desired position.

The locking means include a plurality of easily accessible, door mounted cam locks which easily connect to the cooporating keepers which are affixed to the stationary frame. Both the access door and its cooporating frame are stamped or otherwise machined to an obround or elliptical configuration and to permit maximum accessibility to the area of the fire damper in a minimum space requirement. By employing the obround or elliptical design, the overall dimensions and the cost and the weight of the access door and frame can be greatly reduced over the prior art rectangular access door designs.

It is therefore an object of the present invention to provide an improved access door and frame for use in building construction duct work of the type set forth.

It is another object of the present invention to provide a novel access door and cooperating frame of obround or elliptical configuration.

It is another object of the present invention to provide a novel access door and cooperating frame including sound deadening gaskets at all locations where adjacent materials are in contact.

It is another object of the present invention to provide a novel access door and frame assembly including readily accessible means to lock the access door to the frame assembly.

It is a further object of the present invention to provide a novel access door and frame construction wherein quickly openable and closable locks are provided to removeably secure the access door to the frame assembly.

It is another object of the present invention to provide a novel access door and frame assembly wherein the frame assembly is provided with integral dove tails to facilitate installation and securing to a wall of the air duct system.

It is another object of the present invention to provide a novel access door and frame assembly that is rugged in construction, inexpensive in manufacture and trouble free when in use.

Other objects and a fuller understanding of the invention will be had by referring to the following description and claims of a preferred embodiment thereof,

taken in conjunction with the accompanying drawings wherein like reference characters refer to similar parts throughout the several views and in which:

BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is a perspective view of an access door and frame installed in a wall of a duct system in accordance with the present invention,

FIG. 2 is an enlarged cross-sectional view taken along line 2-2 of FIG. 1, looking in the direction of the arrows.

FIG. 3 is an exploded, perspective view showing the frame assembly and access door.

FIG. 4 is a top plan view showing the frame assembly installed in a duct system with the dove tails bent over to secure the frame to the duct wall.

DESCRIPTION OF THE PREFERRED EMBODIMENT OF THE INVENTION Although specific terms are used in the following description for the sake of clarity, these terms are intended to refer only to the particular structure of my invention selected for illustration in the drawings, and are not intended to define or limit the scope of the invention.

Referring now to the drawings, 1 show in FIG. I a section of duct work wherein an access door and frame assembly 12 has been installed to permit access into the interior of the duct work, for example, to permit servicing a fire damper (not shown). The access door and frame assembly includes a metallic frame 14- and a metallic door 16, both of which are fabricated to cooperating obround configuration to permit maximum access into the interior of the duct system with an opening 18 of minimum dimensions. The obround or elliptical opening 18 has been found to be highly efficient in space utilization and allows greater accessibility for fire damper servicing purposes in less space than previously required by prior art rectangularly configured access door constructions.

The frame 14 is pressed or roll formed from sturdy sheet steel, preferably of 22 gauge thickness, to an obround or elliptical configuration. The frame is inwardly notched or otherwise treated to form a plurality of peripherally spaced dove tails 26 for ease in installation. The frame can be readily secured to the duct work by first positioning the frame 14 in the duct opening 22 and then bending the dove tails 2G individually outwardly until the frame is secured in position, see FIG. 4. The clear frame opening l8 permits easy access to the dove tails during the frame installation procedures. A peripheral gasket 2 interposes between the interior surface 26 of the duct work 10 and the bent dove tails and serves the dual purpose of sealing the connection against air leakage and also prevents the buildup of noise between adjacent metallic parts. I prefer to employ injection molded gaskets (45 shore A durometer) for this purpose which are capable of maintaining an effective seal against pressure up to 10 inches W.C.

As best seen in FIG. 2, the frame 14 is formed to provide an interior peripheral ledge 28 which defines the access opening H8. The ledge forms a firm seat to receive the acess door 16 thereon and in conjunction with the peripheral gasket 30 and the cam locks 32 provides a securely sealed, air tightjunction. The gasket 30 is fabricated of the same material as the gasket 24 and serves the same purpose.

The access door 16 is formed to an obround or elliptical configuration to cooperate with the frame 14 and to seat upon the ledge 28 in complete peripheral contact therewith. Preferably, the door is fabricated of 22 gauge sheet steel and interiorly is filled with suitable insulating material 34. A sheet of aluminum foil 36 interiorly covers the insulating material 34 and is crimped or otherwise peripherally connected to the steel portion of the door construction A plurality of cam locks 32 space about the periphery of the door 16 and rotatively engage in respective 00- operating keepers 40 which are riveted to or otherwise secured to the frame 14 about the clear access opening 18. The cam locks individually turn into the keepers to securely afiix the door 16 to the frame 14 in an air tight, easily openable junction. The cam locks 32 serve to force the door 16 against the interior ledge 28 by compressing the gasket 30 therebetween.

I claim:

1. In an access device suitable for permitting access into the interior of duct work through a duct opening, the combination of A. a frame afiixed to the duct work at the said duct opening and defining an access opening,

1. said frame and access opening being of obround configuration,

2. said frame being formed to provide a peripheral interior ledge,

a. said ledge having an interior surface and an exteriorly facing surface,

3. said frame being equipped with a plurality of stationary cam lock keepers,

a. said keepers being peripherally positioned;

B. a first gasket contacting the interior surface of the ledge,

I. said first gasket being interposed between the frame and the duct work,

2. said gasket being a high pressure gasket capable of maintaining an effective seal against static pressures up to 10 inches w.c.;

C. a door removably affixed to the frame to close the access opening,

1. said door being of obround configuration,

2. said door being of necessary size and configuration to close the access opening,

3. said door coacting with and seating against the interior ledge when closing the access opening,

4. said door having an interior surface facing into the access opening and an exterior surface facing away from the access opening;

D. a plurality of cam locks affixed to the exterior surface of the door in registry above the keepers,

1. said cam locks being turnable into the keepers to retain the door in association with the frame;

E. a second gasket contacting the exterior surface of the ledge,

1. said second gasket being interposed between the frame and the access door,

2. said gasket being a high pressure gasket capable of maintaining an effective seal against static pressures up to 10 inches w.c.;

F. means to squeeze the first gasket between the frame and the duct work,

G. means to squeeze the second gasket between the frame and the access door,

17 said means comprising the said keepers and cam locks,

2. said cam locks being turned relative to the keepers to pull the door toward the frame,

3. said cam locks and keepers squeezing the second gasket between the interior surface of the door and the exterior surface of the ledge. 

1. Irn an access device suitable for permitting access into the interior of duct work through a duct opening, the combination of A. a frame affixed to the duct work at the said duct opening and defining an access opening,
 1. said frame and access opening being of obround configuration,
 2. said frame being formed to provide a peripheral interior ledge, a. said ledge having an interior surface and an exteriorly facing surface,
 3. said frame being equipped with a plurality of stationary cam lock keepers, a. said keepers being peripherally positioned; B. a first gasket contacting the interior surface of the ledge,
 1. said first gasket being interposed between the frame and the duct work,
 2. said gasket being a high pressure gasket capable of maintaining an effective seal against static pressures up to 10 inches w.c.; C. a door removably affixed to the frame to close the access opening,
 1. said door being of obround configuration,
 2. said door being of necessary size and configuration to close the access opening,
 3. said door coacting with and seating against the interior ledge when closing the access opening,
 4. said door having an interior surface facing into the access opening and an exterior surface facing away from the access opening; D. a plurality of cam locks affixed to the exterior surface of the door in registry above the keepers,
 1. said cam locks being turnable into the keepers to retain the door in association with the frame; E. a second gasket contacting the exterior surface of the ledge,
 1. said second gasket being interposed between the frame and the access door,
 2. said gasket being a high pressure gasket capable of maintaining an effective seal against static pressures up to 10 inches w.c.; F. means to squeeze the first gasket between the frame and the duct work,
 1. said means comprising a plurality of dove tails which integrally inwardly extend from the periphery of the frame,
 2. said dove tails being bent about duct work at the duct opening,
 3. said dove tails squeezing the first gasket between the duct work and the interior surface of the ledge; and G. means to squeeze the second gasket between the frame and the access door,
 1. said means comprising the said keepers and cam locks,
 2. said cam locks being turned relative to the keepers to pull the door toward the frame,
 3. said cam locks and keepers squeezing the second gasket between the interior surface of the door and the exterior surface of the ledge.
 2. said frame being formed to provide a peripheral interior ledge, a. said ledge having an interior surface and an exteriorly facing surface,
 2. said cam locks being turned relative to the keepers to pull the door toward the frame,
 2. said dove tails being bent about duct work at the duct opening,
 2. said gasket being a high pressure gasket capable of maintaining an effective seal against static pressures up to 10 inches w.c.; F. means to squeeze the first gasket between the frame and the duct work,
 2. said door being of necessary size and configuration to close the access opening,
 2. said gasket being a high pressure gasket capable of maintaining an effective seal against static pressures up to 10 inches w.c.; C. a door removably affixed to the frame to close the access opening,
 3. said frame being equipped with a plurality of stationary cam lock keepers, a. said keepers being peripherally positioned; B. a first gasket contacting the interior surface of the ledge,
 3. said cam locks and keepers squeezing the second gasket between the interior surface of the door and the exterior surface of the ledge.
 3. said door coacting with and seating against the interior ledge when closing the access opening,
 3. said dove tails squeezing the first gasket between the duct work and the interior surface of the ledge; and G. means to squeeze the second gasket between the frame and the access door,
 4. said door having an interior surface facing into the access opening and an exterior surface facing away from the access opening; D. a plurality of cam locks affixed to the exterior surface of the door in registry above the keepers, 